-LRB- CNN -RRB- The Internet was abuzz last week when the cast of the all-female `` Ghostbusters '' reboot was announced . The crop of funny ladies charged with eliminating the undead are some of the top female comedians working today . The chatter and support has a lot to do with the fans these women have garnered . It also comes from groups and individuals -- male and female -- who long to see more women headlining major Hollywood films .

So , is `` Ghostbusters '' progress ? Yes . Is it a panacea ? No . Let 's talk about why .

Putting women front and center in film is the exception , not the rule . Using `` Ghostbusters '' as an example of how far females have come is like celebrating Kathryn Bigelow 's best director Academy Award -- and forgetting that she 's the only woman ever to take home that honor . You can applaud Katniss , Elsa , and Anna , too . But , they 're following the legions of guys who have protected and ruled the planet , palaces and corporate empires near and far . It 's fair and important to celebrate these high-profile moments of progress . Doing so , however , may dismiss the lack of diversity that persists onscreen and behind the camera in Hollywood movies .

Our annual statistics on women 's participation in the year 's 100 top-grossing films reveal stagnation . In 2013 , only 29 % of 4,506 speaking characters evaluated were female . In another study , we examined popular films from 1990 to 1995 . The percentage was 29 % . For those of you who think the past was better , other research shows that women clocked in at 25 % of characters in a sample of movies from the late 1940s . Interestingly , only 28 % of movies in 2013 depicted a female lead or co-lead .

Behind the camera it 's even worse . Women rarely get to direct large budget features on the scale of `` Ghostbusters '' or `` The Hunger Games . '' Across top-grossing films from 2002 to 2013 , only 4.2 % of all directors were female . In 2013 and 2014 , there were only two female directors each year . Even more dismal figures concern black or African-American female directors . Only three black women were directors across 700 popular movies between 2007 and 2014 .

What drives the lack of diversity in films ? Our studies with industry leaders -LRB- funded by the Geena Davis Institute on Gender in Media and Sundance Institute/Women in Film Los Angeles -RRB- reveal that both in front of and behind the camera , perceptions about market forces and money are to blame for the lack of females . Male leads , stories and properties are seen as more profitable , while female stories and casts are seen as a risk . For female directors , the financing structure , subject matter , and even perceived confidence of filmmakers creates a barrier to career progress .

Much like pesky poltergeists , these myths about profitability will have to be busted before change can occur . To do so , solutions need to be implemented that overcome implicit biases and circumvent stereotyping .

Leveling the playing field when it comes to hiring is one step toward creating a more balanced behind-the-scenes environment . We have previously advocated for a modified version of the NFL 's Rooney Rule : a league-wide commitment to interviewing diverse candidates for coaching positions . Applied to Hollywood , the rule would stipulate that women and candidates from underrepresented backgrounds be considered or even interviewed when hiring film directors .

Another solution we 're implementing at USC Annenberg is to look holistically at the entertainment industry from decision-making to the content we view . The USC Annenberg Comprehensive Analysis and Report on Diversity will `` grade '' companies based on the diversity within their ranks and the media they create . Media conglomerates can be held accountable for their decisions across film , television and digital productions . While not every story should or can be female-dominated or focus on underrepresented racial and/or ethnic groups , examining a slate of content will reveal where and when stories about diverse groups and individuals are valued and told .

Right now , lifting the veil on diversity in Hollywood reveals white men standing behind the curtain . In this environment , casting four women to take care of a metropolitan ghost problem does feel rather extraordinary . Sealing up cracks in the development , casting and hiring pipeline for women and underrepresented groups , however , should result in an onscreen reality that is more representative of the world we live in .

Then , the only unreal thing about `` Ghostbusters '' will be the ghouls and goblins , not the women busting them .

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A `` Ghostbusters '' reboot has been announced with all-female leads

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But lack of diversity persists on screen and behind camera in Hollywood , authors say